1. Field of the Invention
The present invention broadly relates to mounting of instruments, such as an inertia measurement unit, and, more particular, is concerned with a mounting arrangement which provides the capability of slow motion adjustment about panning (vertical) and tilting (horizontal) axes.
2. Description of the Prior Art
The mounting of instruments of various types to provide for freedom of movement about two orthogonal axes is an old, well known art. U.S. Pat. Nos. 378,430 issued in 1888 to Carpenter and 1,177,165 issued in 1916 to Akeley disclose early arrangements for mounting instruments, such as cameras of various types, for movement about horizontal and vertical axes. These arrangements also include features for clamping or holding the instrument at the desired position.
More recently, in 1970 an arrangement for mounting a distance-measuring device for movement in vertical and horizontal directions, for clamping the device at a desired position, and for fine adjustment of the vertical angular position of the device even when it is clamped, was disclosed in U.S. Pat. No. 3,536,248 to Chickering, Jr.
For certain applications, instruments must be of a size and weight which allow them to fit within very tight space constraints, for example when inertial measurement units used in geodetic surveying operations are carried in small helicopters. These applications require a mounting arrangement for the instrument which provides slow motion adjustment capabilities about both horizontal and vertical axes, while being of rugged construction so as to withstand the impact forces and vibrations to be expected in mobile environments.
While the arrangements of the aforementioned patents may accomplish their intended purposes, they do not appear to be fully suited to fulfill the constraints, requirements and environmental parameters expected of mounting arrangements for typical instruments used in mobile geodetic surveying operations. Therefore, a need exists for an alternative mounting arrangement which includes a composite of features tailored to these particular applications.